Millions of people fly during the holidays. Keep your family healthy during this busy travel season. Pack hand sanitizer and antibacterial wipes in your carry-on bag. ​

The website TravelMath recently tackled the issue of airport and airplane hygiene, sending a microbiologist to take bacterial samples from five airports and four flights. First the good news: All 26 samples were negative for E. coli. ​

But the swabs picked up enough other kinds of bacteria to convince you to wipe down these germy surfaces:

Tray tables — Amazingly, the tray tables on planes carry nearly 10 times as much bacteria as the lavatory flush button, according to the TravelMath study. Get in the habit of wiping down your tray table as soon as you get seated.Airport drinking fountain button — Consider covering the button with a facial tissue or using hand sanitizer immediately afterward.

Overhead air vent. After wiping down your tray table, give the overhead air vent some attention. Passengers are constantly reaching up to adjust the air flow and temperature. Those things get filthy.

Lavatory flush button. While it may surprise you that this wasn’t the germiest place of all, it still deserves attention. Wipe it down, and use hand sanitizer afterward.Seatbelt buckle. Everyone touches the seatbelt buckle several times during a flight, so it makes sense that it picks up bacteria.

Bathroom stall lock. Ditto for the lavatory lock. Every time you touch one, you need to wash your hands or use the sanitizer.